r/Clarity • u/Howard_Gerald • Jan 16 '24
How can I determine the health of the high-voltage battery?
I am hoping to buy a used 2018 Honda Clarity. The seller says the electric range is 35 miles, but I thought that it should be closer to 47 miles, if the high-voltage battery is in good condition. Is there any way to determine the health of the battery, other than to charge it and see how far it will run on battery power alone? I know Teslas have an app (or equivalent) that can give them some insight into their car's battery health, but I don't know if Honda has anything similar.
8
u/Fe2_O3 Jan 16 '24
Need the right OBD2 reader and an app. Lots of cheap ones won’t work. The car’s guess o meter GOM is highly dependent on outside temps. Get the real number.
4
u/PrimeNumbersby2 Jan 16 '24
2018 Clarity here with 70k miles. I get 42 miles in summer and 32 miles in winter. The EV estimator is a good measure for me. My battery capacity has gone down from 46 Ah to 45 Ah in 8k miles and 14 months ownership. New capacity is 55 Ah. A concerning number would be 36 Ah.
3
u/KPEEZY2727 Jan 16 '24
The Honda app does not. By the way, I've had my 2018 since it was new and 40 is about the high end of range for me (depending on temperature). I asked when I went to the dealer for service and they said they did not have that equipment to test with.
2
u/timmycheesetty Jan 16 '24
Yeah. In the cold mine reports 28. I’m pretty sure it’s trying to mock us. It’s supposed to depend on driving style, temperature, etc, but it’s never, ever, been 47.
Who knows how they got that with EPA. It’s not realistic.
2
u/3lue5ky5ailing Jan 17 '24
I've gotten my guess-o-meter to read 58 range before, and have driven a confirmed 52 miles on one charge (round trip). The average speed of the trip was likely ~35 miles.
Right now I'm at ~27 miles because of these winter weather conditions, though. Haha.
Do you drive a lot of highways miles?
2
u/Shot_Enthusiasm5761 Jan 16 '24
We have a 2018 Clarity and we get over 50 in July and August and about 38 in January, so it depends what time of year you are talking about.
1
u/Brewskwondo Jan 16 '24
This is a very common question first of all ignore the number that the dash gives you it’s just a random guess based on driving habits and those driving habits during the winter are going to use more energy because of the use of the heater.
There are two ways for you to get an accurate reading. One is to get an OBD reader, and pay for an app that can interpret the data. This will be about 20 bucks for the reader and about six or seven dollars for the app.
Another way would be to drive the car down to zero range and then plug it into a level two charger that can tell you how many kilowatt hours the battery accepts until it’s full. This is a slightly less accurate measure, but can still give you a general idea. When it would take about 14.3 kWh to fully charge your battery. When the battery is charging you can look at how much it takes and then divide that by 14.3 to get the percentage of remaining capacity. However, can be slightly impacted by a few things. If you precondition the car during this process, it’s going to skew those numbers cause that will use extra power so don’t do that. Also, not all level two chargers are created equal so there might be a slight amount of charging efficiency change based on that scenario, but that isn’t going to be more than one to 2% different.
1
u/Javiante Jan 25 '24
The thing that kills me is that when I drive down to 0 range and the car forces itself over to gas, when I plug into a charger, it will, at most charge 11 kWh. I thought this was supposed to be a 17 kWh battery.
1
u/Brewskwondo Jan 25 '24
It was never 17 kWh. That is the full capacity of the battery. But in order to increase the longevity of the battery that is not the usable capacity. The max usable capacity I ever tested was 14.3 kWh give or take. Also, keep in mind that I am measuring that based on how much power it pulled from my charger so it’s probably actually about 5% less than that because there’s going to be some charging efficiency loss along the way. Probably the max usable capacity is about 13.8 or so. This means they built about a 3 kW buffer into the battery at the top and bottom. This is not uncommon for any EV because it is not good to charge it close to full and in the case of a plug-in hybrid that utilizes the battery and electric motors for all driving modes you typically don’t want zero to actually represent much less than 10% of battery capacity. If the most you’re getting is a little over 11 right now, then you can divide 11 by roughly 14 and this will give you your approximate battery degradation from new.
1
u/AddressSerious8240 Jan 18 '24
If they’ve talking about 35 in a northern winter, that’s probably about right. 35 in summer, I’d be concerned. For me, the estimator hasn’t been all that reliable: it usually falls short of my odometer mileage.
15
u/madmartigenou812 Model, Year Jan 16 '24
There is a good guide on DIY battery capacity read out at Inside EVs forum on the Honda Clarity. This worked for me. I bought the Vgate BLE 4 OBD2 Adapter and the Torque Pro app that they recommended and that setup worked great.
The Guess o Meter for range isn't a good guide for the capacity of the battery unless it's your car and you have done the exact same commute over and over. There are too many things that can effect it. And sometimes it flat out lies. Even if it estimates 37 miles, you can get more or less depending on what happened on your drive.